1. Field of the Invention
The present invention is related to an LED lighting device having multiple driving stages, and more particularly, to an LED lighting device having multiple driving stages and capable of providing dual mode operations for two AC voltage ranges.
2. Description of the Prior Art
An LED lighting device directly driven by a rectified alternative-current (AC) voltage usually adopts a plurality of LEDs coupled in series in order to provide required luminance. In a conventional method for driving an LED lighting device, the LEDs may be light up in multiple stages in order to increase the effective operational voltage range.
The voltage and frequency of general-purpose AC electricity vary from country to country throughout the world. Typically, mains electricity either adopts 110-volt (110V), 120-volt (120V), 220-volt (220V) or 230-volt (230V) in voltage and 50-Herts (50 Hz) or 60-Herts (60 Hz) in frequency. For commercial and industrial applications, a higher voltage is often required, such as 277-volt (277V) used in the United States of America. It is to be noted that these voltage values are averages, since the voltage does fluctuate during usage. While a switching-type LED lighting device can operate within a large voltage range (such as 85V-265V), a linear-type LED lighting device is designed to only operate at a specific voltage. More specifically, when a linear-type LED lighting device either adopts a 110V driving scheme or a 220V driving scheme, it can function normally as long as the rectified AC voltage is within a certain small range, such as 110V±10% or 220V±10%. However, when a linear-type LED lighting device adopting the 110V driving scheme is used in a country with 220V mains electricity, system failure may occur due to over-rated power; when a linear-type LED lighting device adopting the 220V driving scheme is used in a country with 110V mains electricity, not all LEDS can be illuminated due to insufficient power. Therefore, there is a need for an LED lighting device having multiple driving stages and capable of providing dual mode operations for two voltage ranges.